Longitudinal assessment of dental erosion-abrasion by cross-polarization optical coherence tomography in vitro.

This study tested a novel in vitro dental erosion-abrasion model and the performance of cross-polarization optical coherence tomography (CP-OCT) in longitudinally monitoring the simulated lesions. Thirty human enamel specimens were prepared and randomized to receive three dental erosion-abrasion (EA) protocols: severe (s-EA, lemon juice/pH:2.5/4.25%w/v citric acid), moderate (m-EA, grapefruit juice/pH:3.5/1.03%w/v citric acid) and no-EA (water, control). EA challenge was performed by exposing the specimens to acidic solutions 4x/day and to brushing 2x/day with 1:3 fluoridated toothpaste slurry, for 14 days. Enamel thickness measurements were obtained using CP-OCT at baseline (D0), 7 (D7) and 14 days (D14) and micro-computed tomography (micro-CT) at D14. Enamel surface loss was measured with both CP-OCT and optical profilometry at D0, D7 and D14. Data was analyzed with repeated-measures ANOVA and Pearson's correlation (r) (α = 0.05). CP-OCT enamel thickness decreased over time in the s-EA group (D0 >D7 > D14, p < 0.001) and m-EA group (D0 > D14, p = 0.019) but did not change in the no-EA group (p = 0.30). Overall, CP-OCT and micro-CT results at D14 correlated moderately (r = 0.73). CP-OCT surface loss was highest for s-EA (p <0.001) but did not differ between moderate and no-EA (p = 0.25). Enamel surface loss with profilometry increased with severity (no-EA>m-EA>s-EA, p < 0.001). D14 surface loss was higher than D7 for both methods except for the no-EA group with profilometry. CP-OCT and profilometry had moderate overall correlation (r = 0.70). Our results revealed that the currently proposed in vitro dental erosion-abrasion model is valid and could simulate lesions of different severities over time. CP-OCT was a suitable method for monitoring the EA lesions.

The threshold of an intra oral scanner to measure lesion depth on natural unpolished teeth.

OBJECTIVES: To investigate the threshold and accuracy of intraoral scanning in measuring freeform human enamel surfaces. METHODS: Software softgauges, ranging between 20 and 160 µm depth, were used to compare four workflow analysis techniques to measure step height on a freeform surface; with or without reference areas and in combination with surface-subtraction to establish which combination produced the most accurate outcome. Having established the optimum combination, 1.5 mm diameter, individual depths ranging from 11 to 81 µm were created separately on 14 unpolished human enamel samples and then scanned with gold standard laboratory optical profilometry (NCLP, TaiCaan Technologies™, XYRIS2000CL, UK) and a clinical intraoral scanner (TrueDefinition™, Midmark Corp., USA). The sequence of surface registration and subtraction determined from the softgauges was used to measure step height on natural human enamel surfaces. Step heights (µm) were compared using two-way ANOVA with post-hoc Bonferroni (p < 0.05) and Bland-Altman analyses. RESULTS: Software differences were significantly reduced from - 29.7 to - 32.5% without, to - 2.4 to - 3.6% with reference areas (p < 0.0001) and the addition of surface-subtraction after registration reduced this further to 0.0 to - 0.3% (p < 0.0001). The intraoral scanner had a depth discrimination threshold of 73 µm on unpolished natural enamel and significant differences (p < 0.05) were observed compared to NCLP below this level. SIGNIFICANCE: The workflow of combining surface-registration and subtraction of surface profiles taken from intraoral scans of freeform unpolished enamel enabled confident measurement of step height above 73 µm. The limits of the scanner is related to data capture and these results provide opportunities for clinical measurement.

Associated risk factors with quantitative erosive tooth wear progression.

OBJECTIVES: The aim of this study was to determine predictors of erosive tooth wear (ETW) progression, using novel primary-care quantitative analysis techniques. METHODS: In a single-centre, prospective, observational cohort longitudinal study, adolescents, aged 11-18 years, underwent a baseline BEWE examination, validated risk factors questionnaire and baseline intraoral scan (IOS, TRIOS 3.0, 3Shape, Copenhagen, Denmark). One year later a repeat scan was taken. Quantitative analysis of wear progression (volume loss) on first permanent molars and upper central incisors was performed using previously published protocols. Multilevel linear regression was used to investigate the associations between baseline predictors and volume loss per mm2. RESULTS: A total of 295 dental surfaces (131 incisors and 164 molars) in 70 patients were analysed for this study. The mean age of participants at baseline was 15.0 years (SD: 0.79), and the average time between scans was 11.8 months (1.61 SD; range 10-13). The mean volume loss per mm2 of dental surfaces was -0.013 mm3 (SD: 0.009). Greater volume loss was observed amongst adolescents with higher baseline BEWE scores and those whose parents had lower education as well as on molar than incisor surfaces. No associations were found with dietary acid intake and intrinsic acid exposure when baseline levels of tooth wear, parental education and other factors were controlled for. CONCLUSIONS: The findings help to characterise groups at greater risk of ETW and would indicate that improved screening and upstream preventative measures should form the basis of a preventative program. CLINICAL SIGNIFICANCE: Intra-orals scans and registration software might improve the ability to diagnose, monitor and prevent the early loss of dental hard tissue.

Excessive tooth wear on human dental enamel: a case report / Desgaste excessivo em esmalte dentário humano: relato de caso

Introduction: although reports on dental erosion have appeared in literature for a long time, there is currently a growing interest among researchers and clinicians about this matter. Potential risk factors for loss of dental hard tissue are changed lifestyle and eating patterns, with increased consumption of acid foods and beverages. Case report: an atypical tooth wear on the buccal surfaces of the mandibular teeth in a 45-year-old woman referred for orthodontic treatment, associated with the frequent consumption of whiskey and lemon, is reported. A comprehensive approach, such as the recognition of dental erosion joined with a careful investigation about eating habits was performed. Ultrastructural examination of replicas of the teeth showed practically structureless enamel and dentin surfaces. Conclusion: the screening for dental erosion in patients seeking orthodontic treatment is advisable to be a usual procedure. Recommendations for treatment and prophylactic measures are made emphasizing the need of multiprofessional attention.

Introdução: embora relatos sobre erosão dentária já apareçam há bastante tempo na literatura, existe atualmente interesse crescente entre pesquisadores e clínicos sobre esse assunto. Fatores que representam riscos potenciais para a perda de tecido duro do dente são as mudanças no estilo de vida e no padrão de alimentação, com o aumento no consumo de alimentos e bebidas ácidas. Relato de caso: lesões atípicas de desgaste dentário na superfície vestibular das unidades inferiores, em uma mulher com 45 de idade, encaminhada para tratamento ortodôntico, associadas ao consumo frequente de uísque e limão, foram relatadas. Uma abordagem abrangente, como o reconhecimento da erosão dentária, em conjunção com a investigação cuidadosa dos hábitos alimentares, foi realizada. O exame por meio da microscopia eletrônica de varredura, realizada em réplicas dos dentes, revelou superfícies de esmalte e dentina praticamente desprovidos de elementos estruturais. Conclusão: sugere-se que uma avaliação direcionada à busca por erosão dentária em pacientes que procuram por tratamento ortodôntico seja um procedimento rotineiro. A atenção multiprofissional, envolvendo o tratamento e o uso de medidas preventivas, é essencial para a adequada atuação junto ao paciente.

Superimposition of sequential scans to measure erosion on unpolished and curved human enamel.

OBJECTIVES: To determine if superimposition of sequential scans can discriminate between different fluorides at step heights less than 5 µm on natural human enamel surfaces. MATERIALS AND METHODS: Natural, unpolished, human enamel specimens (n = 60) were randomly assigned to one of three pre-treatment toothpaste slurries with a calcium silicate/fluoride, fluoride-only and a control. Baseline and post treatment scans, from a non-contacting profilometer with a 0.01 µm z-axis and <1 µm lateral scanning resolution were imported into superimposition software to define change in mean 3D step height and surface roughness following erosion in 0.3% citric acid for 15 min. Statistical analysis conducted with two-way repeated measures ANOVA and post-hoc Tukey's multiple comparisons. RESULTS: Confidence and resolution of superimposition and subtraction of repeated profiles from unpolished enamel revealed accuracy within 1-2 µm. The technique was able to discriminate between the fluorides demonstrating statistical differences in mean (SD) 3D step height (µm) of 1.96 (0.40) and 2.75 (0.49) (p = 0.0024). There was a statistically significant increase in surface roughness for all groups after 15 min erosion compared to baseline. But no statistically significant difference between the interventions after 15 min erosion but there was compared to no fluoride (p = 0.006). CONCLUSION: Superimposition and subtraction of profiles could discriminate between fluoride interventions, which showed statistical differences in enamel loss differences less than 3 µm. CLINICAL SIGNIFICANCE: This erosion model and data analysis workflow was able to distinguish differences between scans of 3 µm on unpolished enamel following the interaction with fluoride.

Cross-polarization optical coherence tomographic assessment of in situ simulated erosive tooth wear.

This clinical study tested cross-polarization optical coherence tomography (CP-OCT) monitoring of erosive tooth wear (ETW). Twenty participants completed a 14-day/arm, 3-arm crossover study simulating different ETW severities. Participants received two enamel specimens (per arm) and were randomized to: severe (s-ETW, lemon juice/pH:2.5/4.25%wt/vol citric acid), moderate (m-ETW, grapefruit juice/pH:3.5/1.03%wt/vol citric acid), and non-ETW (water). Enamel thickness was measured with CP-OCT (day[D] 0, 7, 14) and micro-computed tomography (µ-CT; D14). Enamel surface loss was determined with CP-OCT and optical profilometry (OP; D7, D14). CP-OCT showed higher enamel surface loss for D14 than D7 for m-ETW (P = .009) and s-ETW (P = .040) and differentiated severity at D14 (s-ETW > non-ETW, P = .027). OP was able to differentiate surface loss between days (D7 < D14, P < .001) for m-ETW and s-ETW, and ETW severity effect after 7 and 14 days (non-ETW < m-ETW < s-ETW, P < .001). At D14, CP-OCT and µ-CT were positively correlated (r = .87, ICC = .62). CP-OCT showed potential as a tool for clinical ETW monitoring.

A novel non-destructive technique for qualitative and quantitative measurement of dental erosion in its entirety by porosity and bulk tissue-loss.

OBJECTIVE: To explore the potential of combining non-contact profilometry (NCP) and confocal laser scanning microscopy (CLSM) data to measure the entire erosive process non-destructively and to validate findings using inductively coupled plasma-atomic emission spectroscopy (ICP-AES), scanning electron microscopy (SEM) and surface microhardness (SMH) using the same samples throughout. METHODS: Polished bovine enamel samples (n = 35) were divided into groups (7/group) with similar SMH values. Samples underwent individual erosive challenges (1 % citric acid, pH3.8) for 1, 5, 10, 15 or 30 min under stirring and aliquot extracts were analysed for Ca and P by ICP-AES. SMH was used to measure erosive softening. Profilometry was used to assess bulk volume loss (BVL). Images were captured by SEM. Samples were stained with rhodamine-B (0.1 mM, 24 h) and images captured by CLSM. Image processing was used to determine changes in fluorescent volume for the first 10 µm (ΔFV10) for each enamel sample which were combined with BVL to calculate total lesion volume (TLV). ANOVA, linear regression and Pearson correlation analysis were used where applicable. RESULTS: Surface softening, [Ca], [P], BVL and ΔFV10µm increased with acid erosion duration which were significant by 10 min (P < .01). The Ca:P ratio increased to 1.57 then decreased after 5 min erosion suggesting a sub/surface phase change, which was observed by SEM and CLSM showing significant changes to the enamel surface and subsurface morphology with time. Combination of BVL and ΔFV10 as TLV strengthened the significant correlations with [Ca], [P], and SMH (P < .01). CONCLUSION: This novel combination of CLSM and NCP allows for concurrent non-destructive quantification of the entire erosive process by mineral loss, and qualitatively characterise microstructural changes during dental erosion.

Impact of mucin on the anti-erosive/anti-abrasive efficacy of chitosan and/or F/Sn in enamel in vitro.

The application of stannous ions in combination with fluoride (F/Sn) is one of the central strategies in reducing erosive tooth wear. F/Sn efficacy can be enhanced by adding chitosan, a positively charged biopolymer. For patients with low saliva flow, this efficacy, however, is not sufficient, making further improvement desirable. This could be achieved by combining chitosan with other molecules like mucin, which together might form multilayers. This in-vitro study aimed to investigate the effect of chitosan, mucin, F/Sn and combinations thereof on enamel erosion and erosion-abrasion. Human enamel samples (n = 448, 28 groups) were cyclically eroded or eroded-abraded (10 days; 6 × 2 min erosion and 2 × 15 s/200 g abrasion per day). Samples were treated 2 × 2 min/day with solutions containing either, chitosan (50 or 500 mPas), porcine gastric mucin, F/Sn or combinations thereof after abrasive challenge. Tissue loss was measured profilometrically, interaction between hard tissue and active agents was assessed with energy dispersive spectroscopy and scanning electron microscopy. Chitosan and F/Sn showed the expected effect in reducing tissue loss under erosive and under erosive-abrasive conditions. Neither mucin alone nor the combinations with mucin showed any additional beneficial effect.

Impact of early biofilm on the assessment of initial enamel erosion with swept-source optical coherence tomography.

Objective: This study examined the impact of early biofilm on the tooth surface, during the assessment of initial enamel erosion using swept-source optical coherence tomography (SS-OCT). Method and materials: Forty-five enamel windows of 2 × 4 mm2 were prepared on 23 extracted human teeth. The specimens were exposed to citric acid (pH 3.2) for 30 minutes and randomly divided into three groups (n = 15): Group 1, no biofilm; Group 2, 1-day-old biofilm; and Group 3, 3-day-old biofilm. Specimens in Groups 2 and 3 were inoculated with oral bacteria (Streptococcus sanguinis, Streptococcus mitis, and Actinomyces naeslundii) to produce early laboratory-cultivated biofilms for 1 and 3 days respectively. Surface microhardness (SMH) measurements were taken at pre- (t1) and post-erosion (t2); and SS-OCT scans were done at t1, t2, and post-biofilm cultivation (t3). Integrated reflectivity (IR) of the tooth-air interface (IRsurface) and enamel (IRenamel) were computed from the mean A-scans. Statistical analysis was performed using paired t tests and one-way ANOVA (α = .05). Results: A significant increase in IRenamel was observed at t2 (P < .05). At t3, IRsurface between Group 1 (control) and Group 2 (P = .012) as well as Group 3 (P = .001) were significantly different. Significant variances in IRenamel were perceived between t2 and t3 for Groups 2 and 3 but not for Group 1. Conclusion: As early biofilm affected SS-OCT assessment of initial enamel erosion, they should be removed from the tooth surface prior to OCT procedures..

Detecting early erosive tooth wear using an intraoral scanner system.

OBJECTIVES: To assess the feasibility of detecting and monitoring early erosive tooth wear using a 3D intraoral scanner (IOS) aided by specific software. METHODS: Extracted sound permanent teeth were assembled in two shortened artificial dental arches and scanned at different intervals with an IOS (3Shape TRIOS® 3) before and after an erosion/abrasion protocol (i.e. 1 h up to 24 h immersion in citric acid solution and subsequent brushing). The 3D models obtained at consecutive time points were superimposed with the baseline model using dedicated software (3Shape TRIOS® Patient Monitoring, version 2.1.1.0) and reference surface alignment. Surface profile differences between the baseline 3D model and the respective models from different time points were expressed as tooth substance loss. Non-parametric tests were used to assess the significance of tooth substance loss at different time points. Spearman's correlation was applied between the tooth substance loss at the end of each erosion/abrasion cycle and the immersion time in acid. RESULTS: Significant tooth substance loss (0.08 mm, IQR = 0.05) was detected by the software after 3 h of erosive-abrasive challenge (p = 0.045). The overall median loss increased gradually from baseline to 24 h showing a strong correlation with the immersion time in acid (rs = 0.971, p < 0.01). CONCLUSIONS: The use of an IOS aided by specific software showed good performance for early detection and monitoring of tooth wear in vitro and has promising potential for in vivo application. CLINICAL SIGNIFICANCE: Detection and monitoring of early erosive tooth wear can be reliably aided by intraoral scanning supported by specific software. The measurement error and uncertainty involved in this method should be taken into consideration when interpreting the tooth substance loss measurements. Furthermore, presuming the difficulty in defining reference surfaces in vivo, clinical validation is needed to determine the system's in vivo performance.

Measurement of erosion depth using microcomputed tomography and light microscopy.

Tooth-erosion is the surface loss of dental hard tissue mostly associated with an acid attack. The aim was to compare dentin and enamel erosion depth measurements using micro-computed tomography (microCT) and light microscopy (LM). Enamel/dentin blocks were prepared from caries-free human molar-teeth (N = 12). Teeth were sectioned to a rectangular shape of 4 × 4 × 6 mm. Specimens were treated with water (NC) or 1.0% citric-acid solution (PC). After treatment, specimens were scanned with micro-computed tomography. On completion, specimens were sectioned and observed under a light-microscope. Lesion depth was observed with 10× magnification and images transferred to Simpleware software. Vertical distance from lesion surface to bottom was measured. Pearson correlation test was used to evaluate correlation and Wilcoxon Signed Rank test to evaluate differences in the two-analysis methods. Mean enamel erosion depth was 0.63 and 38.38 µm (microCT) and 0.54 and 39.43 µm (LM) for NC and PC, respectively. Dentin erosion depth was 0.72 and 48.05 µm (microCT) and 0.56 and 49.92 µm (LM) for NC and PC, respectively. There was a significant correlation between the two-analysis methods (r = 0.998; p < .001). No statistically significant difference in results were obtained when microCT and LM were compared (p = .584). This results obtained from the current study suggested that erosion depth measurements made using microCT and LM yielded comparable results. The microCT method is preferred if the conservation of specimens is desired.

Characterisation of mineral loss as a function of depth using confocal laser scanning microscopy to study erosive lesions in enamel: A novel non-destructive image processing model.

OBJECTIVE: The aim was to develop a novel image processing protocol for confocal laser scanning microscopy (CLSM) to study mineral distribution within erosive lesions as a function of depth. METHODS: Polished bovine enamel samples (n = 80) were divided into groups (8/group) with similar mean surface microhardness (SMH) values. Samples underwent erosion (1 % citric acid pH3.8) for 1,5,10,15, or 30 min, with or without stirring giving 10 treatment groups in a 2*5 factorial design. SMH was used to measure erosive softening. Profilometry was used to measure bulk tissue loss. Samples were then stained with rhodamine-B (0.1 mM, 24 h) and imaged using CLSM. Image processing was used to measure fluorescence volume (FV) as a function of depth for each image. The data from reference images were subtracted from post-erosive data to determine changes in fluorescent volume (ΔFV) as a function of depth. 2-way ANOVA and linear regression analysis were used where applicable. RESULTS: Surface softening and bulk tissue loss increased with acid erosion duration with or without stirring. Stirring significantly increased net softening at each time point; specimens underwent significantly more bulk tissue loss (P < 0.05). CLSM showed the erosive lesion deepened as exposure to acid increased, and that at the near surface (0-10 µm) FV and ΔFV increased rapidly for stirred solutions. The increase in pore space translated to a softer surface as measured by SMH. CONCLUSION: This novel non-destructive method allows concurrent quantification of dental erosion by mineral loss as a function of depth, and qualitative characterisation of microstructural changes during early erosion.

Preventive effect of remineralizing materials on dental erosion lesions by speckle technique: An in vitro analysis.

The aim of this in vitro study was to evaluate the preventive effect of different materials on dental erosion lesions by speckle coherent light scattering analysis. Forty bovine teeth were divided in the following groups (n = 10): 1) DURA- Preventive Treatment with Fluoride Varnish (Duraphat, Colgate-Palmolive); 2) ELX- Preventive treatment with Elmex® Erosion Protection Toothpaste (GABA International AG, Therwil, Switzerland); 3) MP- Preventive treatment with MI Paste® (GC America); and 4) REG- Preventive Treatment with Regenerate Enamel Science™ (Unilever). For all groups, each sample was divided into 3 areas: non-treatment (control); preventive treatment + erosive challenge; non-treatment + erosive challenge. The erosive challenge was carried out using Sprite® Zero soft drink (pH 2.58). After the erosive challenge, the samples were evaluated by speckle coherent light scattering method in the eroded area compared to the sound area. The results showed that there was a statistically significant difference between eroded area with and without preventive treatment, however, there was no statistically significant difference among the different preventive materials tested.

Methods of assessment of early dentine erosion: a review.

Dentine erosion is an increasingly recognised problem, especially in aging population, and various methods have been utilised for its assessment. This narrative review was planned to summarise the methods for the assessment of the early stages of dentine erosion. Relevant original articles published in the English language from 2013 to 2017 were reviewed. Laboratory techniques and methods with in vivo potential were separately studied. It is evident that the assessment of early dentine erosion is complex and requires a combination of methods. For clinical evaluation, chemical analysis and optical methods show great potential but are in need of more validation.

Towards quantitative analysis of enamel erosion by focused ion beam tomography.

OBJECTIVES: The purpose of this work is a proof of concept to introduce a new quantitative 3D-analysis of dental erosion obtained by focused ion beam (FIB) tomography associated with silver nitrate penetration into porosities in etched enamel. METHODS: One sample selected was sound enamel after removal of the aprismatic surface. The other was studied after applying an additional attack with orthophosphoric acid. Both surfaces were infiltrated with silver nitrate via immersion. After dehydration, samples were observed in a dual column FIB/SEM station. Serial FIB sectioning was conducted with a current of 3nA at 30keV and an increment step of 20nm for the healthy enamel and of 40nm for the etched one. 3D analysis was performed with Fiji software and BoneJ plugin and several parameters were obtained to characterize the tissue: non-mineralized phase content (NMP), connected porosity fraction (CPF) and degree of anisotropy (DA) of the NMP. RESULTS: Healthy enamel showed an NMP content of 0.5vol.%, with a bimodal distribution of non-mineralized regions, inside the prisms and between the prisms. No silver penetration was noticed in the healthy enamel, demonstrating the absence of open porosity. In contrast, silver nitrate penetration after acidic exposure was observed, up to a depth of 12µm, which allowed the calculation of an interconnected porosity volume fraction (CPF) of 3.1vol.%, mostly between the prisms. Values for DA of 0.56 for sound enamel and 0.81 for acid-etched surface were determined, highlighting a higher degree of anisotropy in the latter. SIGNIFICANCE: Quantitative analysis of FIB tomography using NMP, CPF and DA should contribute to a better understanding and follow up of dental erosion, correlation between erosion and attrition or abrasion process, and the ability to develop enamel remineralization procedures.

A novel electron-microscopic method for measurement of mineral content in enamel lesions.

OBJECTIVE: To assess Scanning Electron Microscopy in Back-Scattered Emission mode (BSE-SEM) for measurement of lesion mineral content as a function of depth. Direct comparison is made with Transverse Micro-Radiography (TMR) and Surface Micro-Hardness (SMH) on carious and erosive lesions. DESIGN: Caries lesions prepared from sound bovine enamel at 37 °C and pH 4.6 in unsaturated (7d) or part-saturated (8d, 4.1 mM Ca2+, 8 mM Pi) lactic acid /methyl cellulose gel system, followed by TMR analysis. Erosive lesions prepared from sound bovine enamel (1% citric acid, pH3.8, room temperature) for 5, 10, 15 or 20 min at n = 10 per treatment group. SMH readings (Vickers diamond, 1.9 N, 20 s) were taken from acid-treated and reference areas of each sample. BSE-SEM performed on polished cross-sections of lesioned samples (Jeol JSM6490LV SEM; high vacuum, 10 keV beam voltage, magnification x500 with constant working distance of 10 mm). Under identical SEM conditions, polished standards i.e. MgF2, alumina, Mg, Al and Si provided a calibration plot of BSE-SEM signal vs. atomic number (z¯). Mineral content vs. depth plots were derived from the cross-sectional BSE-SEM data. RESULTS: Cross-sectional BSE-SEM images clearly differentiate between caries and erosive lesions. Comparison of caries lesion mineral loss from BSE-SEM with TMR data showed good correlation (R2 = 0.98). Similarly, comparison of BSE-SEM data from erosive lesions showed good correlation (R2 = 0.99) with hardness loss data from SMH. CONCLUSION: BSE-SEM provides a relatively rapid and cost-effective method for the assessment of mineral content in demineralised tooth enamel and is applicable to both caries and erosive lesions.

Monitoring the progression of erosive tooth wear (ETW) using BEWE index in casts and their 3D images: A retrospective longitudinal study.

OBJECTIVE: To determine if the Basic erosive tooth wear index (BEWE index) is able to assess and monitor ETW changes in two consecutive cast models, and detect methodological differences when using the corresponding 3D image replicas. METHODS: A total of 480 pre-treatment and 2-year post-treatment orthodontic models (n = 240 cast models and n = 240 3D image replicas) from 120 adolescents treated between 2002 and 2013 at the Gent Dental Clinic, Belgium, were scored using the BEWE index. For data analysis only posterior sextants were considered, and inter-method differences were evaluated using Wilcoxon Signed Rank test, Kappa values and Mc Nemar tests (p < 0.05). Correlations between methods were determined using Kendall tau correlation test. RESULTS: Significant changes of ETW were detected between two consecutive models when BEWE index was used to score cast models or their 3D image replicas (p < 0.001). A strong significant correlation (τb: 0.74; p < 0.001) was shown between both methods However, 3D image-BEWE index combination showed a higher probability for detecting initial surface changes, and scored significantly higher than casts (p < 0.001). Incidence and progression of ETW using 3D images was 13.3% (n = 16) and 60.9% (n = 56) respectively, with two subjects developing BEWE = 3 in at least one tooth surface. CONCLUSIONS: BEWE index is a suitable tool for the scoring of ETW lesions in 3D images and cast. The combination of both digital 3D records and index, can be used for the monitoring of ETW in a longitudinal approach. The higher sensibility of BEWE index when scoring 3D images might improve the early diagnosis of ETW lesions. CLINICAL SIGNIFICANCE: The BEWE index combined with digital 3D records of oral conditions might improve the practitioner performance with respect to early diagnosis, monitoring and managing ETW.

Application of the Self- Assembling Peptide P11-4 for Prevention of Acidic Erosion.

The aim of this study was to use ultrasonography to evaluate the effect of the self-assembling peptide P11-4 on acid erosion prevention. Curodont Repair (CR), which includes peptide P11-4, was used. Rectangular prisms of bovine enamel (4×1×1 mm) were immersed in pure orange juice for a period of 5 minutes six times per day for 28 days. These samples were divided into four groups of six specimens each and treated differently for an additional period of 28 days: 1) baseline group specimens were stored in artificial saliva; 2) CR group specimens were exposed to curodont without acid challenge; 3) NCRA (no curodont+acid challenge) specimens were treated with orange juice without curodont exposure; and 4) CRA (CR+acid challenge) specimens were treated with curodont before treatment with orange juice. The propagation time of longitudinal ultrasonic velocity (UV) was measured. Ultrastructural observation of each tested enamel surface was carried out using field-emission scanning electron microscopy (SEM). The UV data were analyzed using two-way analysis of variance with time and treatment as confounding factors. Post hoc pairwise tests among groups were performed using the Tukey honestly significant difference test. The average UV in intact bovine enamel for the baseline group ranged from 4,483 to 4,549 m/s and did not vary significantly within the test period. The average ultrasonic velocity (UV) in all samples decreased after the initial erosion. The UV in NCRA decreased further over time. Increased UVs were found for CR and CRA. For CR and CRA, there was no significant difference in UV at the end of the experiment from the initial value before erosion. In the results of SEM observation, the CR and CRA groups had similar morphologic features in that etching patterns were not clearly due to precipitation between the enamel rods. From the results of this in vitro study, it might be concluded that applying enamel matrix derivatives and self-assembling peptides on erosive lesions can improve remineralization.

3D-Image analysis of the impact of toothpaste abrasivity on the progression of simulated non-carious cervical lesions.

OBJECTIVES: To investigate the effect of toothpaste abrasive level on the progression of non-carious cervical lesions (NCCLs) using 3D-image subtraction. METHODS: Upper first premolars were allocated into seven groups (n = 16) of toothpaste/abrasive slurries: A-Zeodent113/5%, B-Zeodent124/10%, C-Zeodent103/15%, D-Sensodyne Pronamel, E-Crest Cavity-Protection, F-Crest Pro-Health-Whitening, and G-Deionized water (DIW). Teeth were mounted on acrylic blocks, and their root surfaces covered with acrylic resin, except for 2-mm near the cemento-enamel junction that was exposed to toothbrushing. Specimens were brushed with the slurries for 5000-, 15,000-, 35,000- and 65,000-strokes. Impressions were taken at baseline and after each brushing time, and then scanned by a 3D optical profilometer. Dentine volume loss was calculated by image subtraction software and subjected to mixed-model ANOVA and multiple comparison tests (α = 0.05). RESULTS: No significant differences among slurries were observed at 5000 and 15,000. At 35,000, F showed higher loss than all other groups except C, which did not differ from the others. At 65,000, F (4.19 ±â€¯3.29 mm3) showed the highest loss, followed by C (2.33 ±â€¯1.47 mm3), which differed from all the other groups except B (1.85 ±â€¯0.91 mm3). Groups B, A (1.35 ±â€¯0.65 mm3), D (1.17 ±â€¯0.48 mm3), E (1.40 ±â€¯0.68 mm3) and G (1.12 ±â€¯0.73 mm3) did not differ from each other. Groups F and C showed significant increase of volume loss starting at 35,000, while B, A, D and E only at 65,000; no increase loss was observed for G. CONCLUSIONS: 3D-image subtraction was able to quantify and differentiate tooth loss, but only at advanced stages. The progression of NCCLs was more evident and faster for highly abrasive slurries. CLINICAL SIGNIFICANCE: Upon root dentin exposure, brushing with lower abrasive dentifrices is advisable to reduce the risk for NCCLs development.

An in-situ pilot study to investigate the native clinical resistance of enamel to erosion.

OBJECTIVES: To investigate the differences in susceptibility of the surface of native and polished enamel to dietary erosion using an in-situ model. METHODS: Thirty healthy volunteers (n = 10 per group) wore mandibular appliances containing 2 native and 2 polished enamel samples for 30 min after which, the samples were exposed to either an ex-vivo or in-vivo immersion in orange juice for 5, 10 or 15 min and the cycle repeated twice with an hour's interval between them. Samples were scanned with a non-contacting laser profilometer and surface roughness was extracted from the data, together with step height and microhardness change on the polished enamel samples. RESULTS: All volunteers completed the study. For native enamel there were no statistical difference between baseline roughness values versus post erosion. Polished enamel significantly increased mean (SD) Sa roughness from baseline for each group resulting in roughness change of 0.04 (0.03), 0.06 (0.04), 0.04 (0.03), 0.06 (0.03), 0.08 (0.05) and 0.09 (0.05) µm respectively. With statistical differences between roughness change 45 min in-vivo versus 45 min ex-vivo (p < 0.05). Microhardness significantly decreased for each polished group, with statistical differences in hardness change between 30 min in-vivo versus 30 min ex-vivo (p < 0.05), 45 min in-vivo versus 30 min ex-vivo (p < 0.01), 45 min in-vivo versus 45 min ex-vivo (p < 0.01). CONCLUSIONS: The native resistance to erosion provided clinically is a combination of the ultrastructure of outer enamel, protection from the salivary pellicle and the overall effects of the oral environment. CLINICALTRIALS. GOV IDENTIFIER: NCT03178968. CLINICAL SIGNIFICANCE: This study demonstrates that outer enamel is innately more resistant to erosion which is clinically relevant as once there has been structural breakdown at this level the effects of erosive wear will be accelerated.